Publish your mock site.  Remember, this can be found in your dashboard toward the top.  It will say,

Your site is currently displaying a “Coming Soon” page. Once you are ready to launch your site click here.

Once you publish your site, we can all practice signing up for an account, commenting, and moderating site content.

I will publish mine first.  Feel free to go to it, sign up and do some commenting.  My mock site is located here.